That depends. We got one paid for by the seller of our house and in the first year it paid for an HVAC repair and plumber. I renewed it once for $600/year and wound up getting our refrigerator replaced in-kind, probably a $1500-2000 machine.
I decided my luck had run out and so I _did not_ renew it again, and we haven't had any other issues that _would have been covered_ since then, so I think I played my cards right.
I don't think they are a scam, but they are an insurance product, and insurance products have a lot of detail that need to be understood before you can decide whether it meets your needs or not. It's not a panacea to home-ownership woes.
Problem is most of them are paid for by the seller who doesn't care about customer service. If your HVAC really was bad they will replace it when they must, but their incentive is to do the cheap repairs as long as possible, instead of the expensive do it right: hoping that eventually you give up and replace it yourself.
If people regularly paid for the yearly subscription they would have incentive to service the customer, but this would increase their costs and most people are not willing to pay the true yearly costs.
